code: def testDFS(self):
      g = Graph.Tree(10, 2)
      vs, ps = g.dfs(0)
      self.assertEqual(vs, [0, 2, 6, 5, 1, 4, 9, 3, 8, 7])
      self.assertEqual(ps, [-1, 0, 2, 2, 0, 1, 4, 1, 3, 3])
  
file_path: python-igraph/tests/test_iterators.py
imports: import unittest
  from igraph import Graph
label_desc: Use image node_id 3 for calling the IteratorTests obj's underlying member method code with example usage: obj.testDFS() without return types